Rewiring the brain
10 December 2008
The researchers worked with rats, which use their whiskers to sense their environment. They trimmed some of the whiskers on both sides of the rats, which meant that one part of the brain received no sensory input while neighbouring areas received normal stimulation. The authors compared the connections among the nerves in both areas of the brain two to six weeks later. Computer analysis of 3D images let them track the parts of nerve ells that send and receive signals in response to the whiskers.
The lack of sensation had little effect on the parts of the cell that receive signals from the whiskers. But things were different in the cell axons, which transmit signals. In brain areas that received input from the whiskers, more of the axons were in close proximity to the receiving cells. Oddly, however, this proximity didn’t foster more connections between the sending and receiving cells.
The authors suggest that this reflects the difference between learning capacity and actual learning. Areas of the brain that receive input from the whiskers have a higher capacity to form connections among nerve cells owing to the close proximity. But that capacity will only be used if the nerves have something important to say.
Image: Pyramidal neurons forming a network in the brain; Dr Jonathan Clarke/Wellcome Images
References
Cheetham CE et al. Altered sensory experience induces targeted rewiring of local excitatory connections in mature neocortex. J Neurosci 2008;28(37):9249-60.